Small addendum... Skyrim sold over 30 Million copies as of 2016. That's not counting Special Edition sales after 2016 (it released in October 2016), Switch (2017), VR (2017-2018), or Anniversary Edition (2021). Now, that might not make it compete with RDR2 (50 Million... while RDR1 was around 23 Million), but it likely puts it into competition with Witcher 3. Right before the release of anniversary edition, Todd Howard said Skyrim had sold "far above" 30 Million copies, but declines to say how much (https://www.windowscentral.com/bethesda-game-studios-single-player-games). Skyrim is a weird case of a game having really long legs beyond release, which gives it comparable sales longevity to games like Minecraft (though definitely NOT on the same scale), GTAV, RDR2, and some live service titles (the same cannot be said for any other Bethesda titles though). I would say Starfield performs more like the Fallout series (just okay in terms of sales) rather than Skyrim, but who knows.
If Larian wants to give BG3 absurd sales legs, cultivating a modding community with easy-to-use tools (and maybe AI-based voice acting) could give it a life beyond initial release. That or free add-ons or DLC.
All of this to say that Skyrim is *potentially* the most successful RPG of all time (though not definitely... don't know how new numbers compare to Witcher... Damn your secrets Todd Howard)
Oh, interesting! I thought 30 million was the recent number - not the number as of 2016. Well then it is most likely competing with The Witcher 3 and Red Dead Redemption 2 (although it has been out significantly longer than RDR2). But I would also agree with your assertion that Starfield is likely to perform more like Fallout than it is like Skyrim - just because the genre doesn't tend to perform as well as high fantasy. It is why I find it hard to believe that Fallout 5 will outsell or be more popular than TES6 when they both eventually come out. It's the same reason I'm not sure Cyberpunk will ever be as successful as The Witcher for CDPR and such. The only exceptions are if the fantasy game that comes out just isn't very good and the sci-fi, post apoc, etc. game is exceptionally well made.
The other exception to this is Grand Theft Auto... and I think this conversation ends up becoming meaningless in terms of "most popular game of the decade/recently" given that I believe GTA6 will stomp all of the other titles mentioned above. GTA5 is at like 175 million sales and that is obviously influenced by GTA Online... but you can bet they are going to put everything they have both into the single player and online mode. I see no way the next installment of GTA doesn't double up games like Starfield, Cyberpunk, etc. in sales.
